Before you comment, Yes I know…Romans invented Concrete. I am referring to a Trolley Bridge constructed of concrete! You only have to view the first three minutes…last two is simply walking back….see a still photo at www.stuffthatsgone.com In 1908 (Sorry vid says 1912), the West Penn Railways experimented with concrete -(-I was corrected several times on my narration…what do you want for a one take video!) for two trolley bridges in Allison PA a Coal and Coke Patch town in Fayette County, southwestern PA along PA 166. This was not done anywhere else on the route, where iron and wood trestles were the building material of the day. The bridge still stands today, and has a special place in cinema history. In 1984 Natassja Kinski starred in a box office bomb, “Maria’s Lovers” a world war 2 story set in Brownsville and Allison. there was a scene when John Savage, her lover, rode a motorcycle across the trolley bridge–this scene unfortunately was cut.